Hi all. I built an SSE awhile back, and I'm finally getting some free time to listen to it on the regular. Right away, I've found that it doesn't sound very good. Muddy. Almost muffled sound. I've tried other amps with the same speakers and they sound clear as a bell, so I suspect maybe something is up with my SSE.
Mine is built in the standard configuration. It has motor cap and choke. Tubes are EL34, and the output transformers are Toroidy TTG-EL34SE.
To those who might be willing to help me figure this out: What information do you need from me? Would photographs help? Any other part numbers you need? I'd love to get this sorted, as I think this amp has lots of potential. So I'm happy to provide any additional info.
Thanks in advance, Tubelab gang!
Mine is built in the standard configuration. It has motor cap and choke. Tubes are EL34, and the output transformers are Toroidy TTG-EL34SE.
To those who might be willing to help me figure this out: What information do you need from me? Would photographs help? Any other part numbers you need? I'd love to get this sorted, as I think this amp has lots of potential. So I'm happy to provide any additional info.
Thanks in advance, Tubelab gang!
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The speakers are Bozak B-401 Rhapsody, with upgraded crossovers. I have no impedance curve for them, per se. I don't suspect the speakers, as they sound just fine when using other amps. The problem seems to lie in the SSE itself.
I found this other forum post here about an SSE with the same OPTs as mine "lacking brightness" and the issue in that case was one of input wiring. I will check my amp to see if my input wiring is correct.
Another thing that I noticed; perhaps this is normal behavior; but when sending signal to the amp while speakers are disconnected, I can clearly hear the signal issuing from the output transformers themselves. Somewhat alarming. It goes away as soon as speakers are connected.
I found this other forum post here about an SSE with the same OPTs as mine "lacking brightness" and the issue in that case was one of input wiring. I will check my amp to see if my input wiring is correct.
Another thing that I noticed; perhaps this is normal behavior; but when sending signal to the amp while speakers are disconnected, I can clearly hear the signal issuing from the output transformers themselves. Somewhat alarming. It goes away as soon as speakers are connected.
Singing transformers and capacitors is normal. Even resistors can sing along. Microphonics and magnetostriction, perhaps piezoelectric effects, are main reasons for the sing-along.
Regarding the poor high end... I once wired one of the windings (I think the secondary) the wrong way. Meaning the negative end (supposed to be gnd) went to the output and the 8ohm output went to gnd. This had the effect of killing the frequency response drastically, and it sounded very muffled.
The reason is the windings in the transformer have capacitance to each other, and it is very important that windings has the signal in phase. If connected so they are out of phase, the capacitance becomes much worse, it has a 'miller effect' in a way b/c when out of phase the voltage swing over the internal capacitance is multiplied by the ratio of those windings. Hmm I am having trouble explaining.
Anyways, perhaps double check the OPT connections are correct.
Regarding the poor high end... I once wired one of the windings (I think the secondary) the wrong way. Meaning the negative end (supposed to be gnd) went to the output and the 8ohm output went to gnd. This had the effect of killing the frequency response drastically, and it sounded very muffled.
The reason is the windings in the transformer have capacitance to each other, and it is very important that windings has the signal in phase. If connected so they are out of phase, the capacitance becomes much worse, it has a 'miller effect' in a way b/c when out of phase the voltage swing over the internal capacitance is multiplied by the ratio of those windings. Hmm I am having trouble explaining.
Anyways, perhaps double check the OPT connections are correct.
😱 You should NEVER run a tube amp without a load!😱
The back EMF will spike and can fry your output transformer.
I can't find much info on those speakers, but being a three-way, they could be a very reactive load. What kind of amplifier have you listened to them on when they sound okay?
Thanks for the heads up! I shall never again run the amp without speakers connected.
When I was running tests, I used a little Class D amplifier I had around, and also an 80s-era Technics integrated. Both sounded splendid with the Bozaks.
When I was running tests, I used a little Class D amplifier I had around, and also an 80s-era Technics integrated. Both sounded splendid with the Bozaks.